THE PREPARATION OF CULTURE MEDIA 15 



successfully upon this iron - gelatine, amongst which 

 he mentions the malignant oedema and the typhoid 

 bacillus in particular as producing such quantities of 

 sulphuretted hydrogen in this medium that, not only 

 did the gelatine in the immediate vicinity of the growth 

 become black, but the whole of the culture material as 

 well (see also p. 410 in tabulated description of typhoid 

 bacillus). 



In order to cultivate organisms in this material at 

 a higher temperature it is necessary to use agar-agar. 

 In addition to the iron solution a small quantity oi 

 a 5 per cent, solution of sodium sulphate and some 

 glycerin should be added. 



Fromme states that he was unable to discover any 

 organisms in the Marburg water which produced sul- 

 phuretted hydrogen in any marked quantity, althougl 

 this was riot regarded by any means as an unimpeach- 

 able supply, and must have contained along with the 

 ordinary water bacteria many organisms derived from 

 polluting sources. 



Another method of qualitatively testing for the pro- 

 duction of sulphuretted hydrogen by bacteria in liquic 

 media is the well-known one and that employed am 

 recommended by Stagnitta-Balistreri. 1 Pieces of lead- 

 paper are suspended in the inoculated flasks or test-tubes 

 containing broth with or without peptone, and the 

 change in the colour produced noted from deep black to 

 pale brown. During the investigations the lead-papei 

 must be daily observed, as, although the reaction ma} 

 be distinct at one time, it may subsequently disappear. 



An interesting table is given of the amount oi 



1 * Die Verbreitung der Schwefelwasserstoffbildung unter den Bak- 

 terien,' Archiv filr Hygiene, 1892. See also ' Beitrage zur Biologie dei 

 krankheitserregenden Bakterien, insbesondere tiber die Bildung voi 

 Schwefelwasserstoff,' Petri and Maaszen, Arbeiten a. d. kaiserlichen Ge- 

 sundheitsamte, vol. viii. 1892, p. 318. 



